1. Field of the Invention
The present invention relates to a vehicle speed signal falsification detection apparatus (a vehicle speed signal tampering detection apparatus) and to a vehicle speed signal falsification detection method (a vehicle speed signal tampering detection method) for detecting that a vehicle speed signal has been illicitly reduced, and a vehicle speed limiting apparatus and a vehicle speed limiting method for limiting a vehicle speed when a vehicle speed signal has been tempered with.
2. Description of Related Art
Currently, a heavy vehicle in Japan is required to be provided with a speed limiter, which prevents the vehicle from traveling at a speed that exceeds a predetermined vehicle speed, as disclosed in Japanese Laid-Open Patent Application No. 2003-148193. When a vehicle speed reaches a target limiting speed, the speed limiter restricts the amount of fuel injection into an engine, thereby suppressing acceleration.
However, if a vehicle speed signal is falsified by various methods, then even when an actual vehicle speed exceeds a target limiting speed, the amount of fuel injection will not be restricted, allowing a speed limiter to be illegally deactivated.